Related Concept Videos
01:11Channel Rhodopsins
Most organisms use photoreceptors to sense and respond to light. Examples of photoreceptors include bacteriorhodopsins and bacteriophytochromes in some bacteria, phytochromes in plants, and rhodopsins in the photoreceptor cells of the vertebral retina. The light-sensitive property of these receptors is because of the bound chromophores, such as bilin in the phytochromes and retinal in the rhodopsins.
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
01:18Other Unique Bacteria
Magnetic bacteria exhibit a directed movement called magnetotaxis, driven by structures called magnetosomes. These magnetosomes consist of chains of magnetic particles made of either magnetite (Fe₃O₄) or greigite (Fe₃S₄) and are organized in a linear conformation by a protein scaffold within invaginations of the cell membrane. The bacteria align along the north–south magnetic field lines, much like a compass needle. They are typically microaerophilic or anaerobic and are commonly found near the...
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
01:22Photoreceptors and Visual Pathways
At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category, whereas...
01:15The Antenna Complex
Plants and other photosynthetic organisms comprise pigments capable of absorption of direct sunlight. These pigments are present in the reaction center - the main site of photochemical reactions as well as in the antenna complex. Under average light conditions, the rate at which reaction center pigments absorb light is far below the electron transport chain's capacity. As a result, the reaction center alone cannot provide enough energy to drive photosynthesis. The photosynthetic efficiency can...
02:32Position-effect Variegation
In 1928, a German botanist Emil Heitz observed the moss nuclei with a DNA binding dye. He observed that while some chromatin regions decondense and spread out in the interphase nucleus, others do not. He termed them euchromatin and heterochromatin, respectively. He proposed that the heterochromatin regions reflect a functionally inactive state of the genome. It was later confirmed that heterochromatin is transcriptionally repressed, and euchromatin is transcriptionally active chromatin.
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Related Experiment Video
Updated: May 31, 2026
09:32
Light-mediated Reversible Modulation of the Mitogen-activated Protein Kinase Pathway during Cell Differentiation and Xenopus Embryonic Development
Published on: June 15, 2017
Human cryptochrome exhibits light-dependent magnetosensitivity.
Lauren E Foley1, Robert J Gegear, Steven M Reppert
1Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
Nature Communications
|June 23, 2011
Summary
Human cryptochrome 2 (CRY2) can act as a light-dependent magnetosensor. This finding suggests humans may possess a magnetic sense, opening new avenues for sensory biology research.
Area of Science:
- Sensory Biology
- Biophysics
- Genetics
Background:
- Many animals possess a magnetic sense for navigation, utilizing the Earth's magnetic field.
- A leading hypothesis suggests magnetosensing involves light-dependent chemical reactions mediated by cryptochrome (CRY) proteins.
Purpose of the Study:
- To investigate the potential magnetosensing capabilities of human cryptochrome 2 (hCRY2).
- To determine if hCRY2 can function as a magnetosensor in a biological system.
Main Methods:
- Utilized a transgenic approach in Drosophila (fruit flies).
- Expressed human CRY2 in Drosophila to assess its function in their magnetoreception system.
- Investigated the light-dependent nature of hCRY2's potential magnetosensing activity.
Main Results:
- Human CRY2 (hCRY2) demonstrated functionality as a magnetosensor within the Drosophila system.
- The observed magnetosensing activity of hCRY2 was dependent on light.
- hCRY2 is highly expressed in the human retina, suggesting a potential ocular basis for magnetosensing.
Conclusions:
- Human CRY2 possesses the molecular capacity to function as a light-dependent magnetosensor.
- This research reopens the possibility of a magnetic sense in humans.
- Further exploration of human magnetoreception is warranted.